Created attachment 453926 [details] dmesg | egrep -i -e 'amd|fb|drm|graphic' I recently installed a new ATI R9 380 into my PC using the amdgpu kernel driver. Previously I had a Nvidia GTX 660 using the nouveau kernel driver. Since then I do not see any console (or boot message) output from the point at which amdgpufb gets loaded until the moment X11/sddm is started. If I press Strg+Alt+F1 through Strg+Alt+F6 in order to switch to a virtual terminal nothing happens. I do a pure UEFI boot with no boot loader by means of the UEFI stub from the linux kernel. I see the boot messages as long as "simplefb" is used but as soon as "amdgpufb" get loaded the screen becomes black.
I found the solution. In contrast to "nouveau" the "amdgpu" driver needs the kernel option DRM_FBDEV_EMULATION to be set. See: https://bugs.freedesktop.org/show_bug.cgi?id=93522
